Mobile radio telephone with reduced key set

ABSTRACT

The invention provides the possibility of reducing the size of a mobile phone ( 1 ) by reducing the key set ( 7, 11, 12, 13 ). 
     The invention provides a system and a method for mobile radio transmission by means of a mobile unit ( 1 ) which, for setting up a connection, has only one or more direct connection keys ( 7, 11, 12, 13 ), the initial activation of which in each case sets up a connection to a destination location assigned to one of the respective direct connection keys ( 7, 11, 12, 13 ). By activation of a central key ( 7 ) of the mobile unit ( 1 ), a connection ( 33 ) from the mobile unit ( 1 ) to a central switching device ( 30 ) is set up.

The present invention relates to a method and a system for mobile radiotransmission by means of a mobile unit.

In mobile radio telephones (mobile phones) the size and the weight ofthe mobile phone is a decisive factor for the user. This means that if amobile phone is smaller and lighter in weight, it can be carried moreconveniently by the user and be available at all times. Meanwhile, theprocess of reducing the size of conventional mobile phones has reached alimit which it seems virtually impossible to overcome. The length of amobile phone in the operational state is defined by the distance betweenthe user's mouth and one of his ears. For this reason, when the mobilephone is in the state in which it is not ready to be spoken into itslength can be reduced further by, for example, folding it up.

Therefore, it has become apparent that the keypad is a decisive factor,in particular for the width dimension of a mobile phone. Usually, amobile phone has the ten immediately required dialling keys togetherwith a number of further keys for additional functions so that as a ruleapproximately 20 keys are arranged on a keypad on the upper side of amobile phone. Technically it is possible to implement an overall furtherreduction in size of the keys of the keypad in order to reduce the sizeof the mobile phone, but there are natural limits to the reduction insize in that it must be possible for a finger of a hand of an adult tobe able to activate a key reliably and clearly. This means that thedistance between two keys must be at least such that when a key isactivated an adjacent key is not undesirably activated also undercircumstances. Even if, in order to reduce the size of the keypad, mostadditional function keys are omitted, at least the ten keys which arenecessary for dialling a number together with an on/off switch are left.There is also the problem that in particular the reduction of the widthof conventional mobile phones has reached a limit.

The object of the present invention is therefore to design a mobileradio transmission system in such a way that a particularly compactdesign of the associated mobile phone is made possible.

The invention is based on the idea that the key set can be severelyreduced and the operational capability of the mobile phone isnevertheless completely ensured if access to specific functions of themobile unit are exported, for example, into an intelligent switchingservice.

The invention therefore provides a method for configuring a mobile unit,the mobile unit having one or more dialling keys. All of the diallingkeys are each assigned one connection destination. By activating adialling key it is thus possible to connect exclusively to the assignedconnection destination. The assignment to a central key is made here insuch a way that the user of the mobile unit cannot change it directly byaccessing the mobile unit.

This means that according to the invention the mobile unit does not haveany keys which serve in the conventional sense for exclusively inputtinga digit but rather that the mobile unit has only connection set-up keyswhich permit a connection set-up to a pre-programmed connectiondestination by means of a single activation (direct dialling keys). Beactivating a central key of the mobile unit a connection is set up fromthe mobile unit to a central switching device, for example.

A password table which contains subscriber data with a respectivelyassigned password can be stored in the central switching device. Afterthe set-up of the connection from the mobile unit to the centralswitching device, subscriber data and a password are then transferredfrom the mobile unit to the central switching device. The centralswitching device then compares the transferred subscriber data and/orthe transferred password with the data stored in the password table. Inthe event that this comparison results in a correspondence between thetransferred subscriber data and the transferred password with thecorresponding data in the password table, the central switching devicethen forwards the connection of the user of the mobile unit as desired.Since, according to the invention, it is not necessary to key in a codeto activate the mobile unit, the user's security, for example in theevent of a theft or other loss of the mobile unit, is ensured by thepassword which is to be transferred to the central switching device.

The assignment of a connection destination to in each case one of theconnection set-up keys, with the exception of the central key, can becarried out here by means of a data transfer from the central switchingcentre to the mobile unit. It should be noted here that owing to thereduced key set, i.e. owing to the fact that only the aforesaid directdialling keys are provided on the mobile unit, programming (assignment)of a connection destination to one of the connection set-up keys cannotbe carried out at the mobile unit by the user himself.

As an alternative, or in addition, for the assignment of a connectiondestination to in each case one of the connection set-up keys, with theexception of the central key, the mobile unit can be inserted into abase station, the assignment then being carried out by means of a datatransmission from the base station to the mobile station.

The base station can simultaneously serve as a charger station. Thismeans that when the mobile unit is inserted into the base station anaccumulator in the mobile unit can be charged at the same time.

In the password table of the central switching device, a list ofpreferred connection destinations can be assigned in each case to apassword and/or to respective specific subscriber data. The function ofa personal telephone directory is thus made possible.

A particularly simple method of operation is obtained if the activationof the central key firstly switches on the mobile unit, a furtheractivation of the central key then sets up the connection to the centralswitching device, yet another activation of the central key releases theconnection to the central switching device and a further activation ofthe central key then switches the mobile unit off again.

The mobile unit can preferably have a key lock, preventing the mobileunit from being switched on unintentionally. The key lock can bowovercome, for example, by a combination of a plurality of keys or bypressing a key for a predefined period of time.

One of the connection set-up keys can be assigned an emergency-callconnection destination. By pressing once on this emergency-call key, aconnection can thus easily be set up to an emergency-call organization,which is advantageous in particular for people for whom it is notpossible to compose a complete number using conventional dialling keysbecause of physical and/or mental disabilities.

According to a further aspect of the invention, a mobile radiotransmission system is provided with at least one mobile unit and onecentral switching centre. For performing connection set-ups, the mobileunit here has merely one or more keys, which, by being activated once,can set up a connection, in the manner of a direct dialling operation,to a connection destination which is assigned to the respective key. Acentral key to which a central switching device is assigned as apermanently pre-programmed connection destination is provided here.Permanently pre-programmed is intended to mean here that it is notpossible, at least for the user of the mobile unit, to assign to thecentral key any connection destination other than the central switchingdevice.

The central switching device can have a password table which containssubscriber data with a respectively assigned password. It is possible toprovide a device by means of which, after the set-up of the connectionfrom the mobile unit to the central switching device, subscriber dataand a password can be transferred to the central switching device. Adevice for comparing the transferred subscriber data and/or thetransferred password with the password table is then provided in thecentral switching device.

In the event that the call transfer by the central switching device doesnot take place, because, for example, the desired subscriber iscurrently engaged, a redial function may be provided in the mobile unit,for example by means of the central key, so that by simply activatingthe central key again without cooperation a renewed dialling attempt canbe carried out.

In the central switching device, it is also possible to provide a devicefor assigning a connection destination to in each case one of theconnection set-up keys, with the exception of the central key, theassignment being effected by means of a data transfer from the centralswitching centre to the mobile unit.

The mobile radio transmission system can be provided with a base stationinto which the mobile unit can be inserted in order to carry out anassignment (programming) of in each case one connection destination toone of the connection set-up keys, with the exception of the centralkey, by means of a data transfer from the fixed station to the mobileunit.

The base station can simultaneously be a charger station which, when themobile unit is in the inserted state, charges an accumulator in saidmobile unit. The base station can have all the functions of aconventional telephone and in particular a hands-free talking facility.

A list of preferred connection destinations, which is assigned to apassword and/or to specific subscriber data, may be provided in thepassword table of the central switching device.

The invention will now be explained in more detail by means of exemplaryembodiments and with reference to the accompanying drawings, in which:

FIGS. 1a and 1 b show a first exemplary embodiment of a mobile unit asis used in the present invention in accordance with a first exemplaryembodiment,

FIGS. 2a and 2 b show a further mobile unit, as is used in the presentinvention in accordance with a further exemplary embodiment,

FIG. 3 shows a mobile unit in the state in which it is inserted into abase station in accordance with the invention,

FIG. 4 shows an internal design of a mobile unit in accordance with thepresent invention, and

FIG. 5 shows a schematic view of a system according to the invention formobile radio transmission.

FIGS. 1a and 1 b show a mobile unit 1 as is used in the presentinvention. The mobile unit 1 has here an antenna 2, a casing 4, aloudspeaker 3 and a microphone 8. The distance between the loudspeaker 3and the microphone 8 corresponds essentially to the distance between themouth of an adult and one of his ears. The length of the mobile unit 1is determined essentially by the distance between the loudspeaker 3 andthe microphone 8. The width of the mobile unit 1 which is illustrated inFIGS. 1a and 1 b is, for example, 2 to 3 cm. This small width of themobile unit 1 is, as is clear, made possible by the fact that aconventional keypad comprising a plurality of keys, each for inputtingone digit, is not provided on the surface of the mobile unit 1, i.e. onthe casing 4 of the mobile unit 1. The mobile unit 1 according to theexemplary embodiment illustrated in FIG. 1 has just one key, namely acentral key 7. If this central key 7 is pressed once, the mobile unit 1is switched on. Directly after operation, after successful authorizationchecking of the inserted SIM card there is immediately the search for anaccessible mobile radio network. The flashing of a network diode 5 showshere that the search process is being carried out. When the networkdiode 5 lights up uninterruptedly this indicates that a networkconnection has been successfully found. After this process of searchingfor and signing onto a mobile radio network, the mobile unit 1 is thenin a state in which it can be dialled up in the same way as aconventional mobile phone. It is not necessary to input a so-called PINcode manually in order to activate the mobile unit 1 because, as statedabove, internal checking of the authorization is carried outautomatically.

The network diode 5 can also have the function that a change in thecolour of its light, for example from green to red, indicates the statusin which a connection has been set up.

The mobile unit 1 also has a volume controller for the loudspeaker 3,which is however not illustrated.

In the switched-on state of the mobile unit 1, calls can thus bereceived. These calls may be signalled audibly, visually or byvibration. In the exemplary embodiment illustrated in FIGS. 1a and 1 b,a call is represented by means of an LED 5. This call LED 5 flashes whena call is received, and lights up continuously while a call is beingmade. By pressing the central key 7 it is possible to terminate again anongoing call. When the call is terminated, the call LED 5 thus goes out.

An explanation of how outgoing calls can be made from the mobile unit 1will now be given below. The condition for this is firstly that themobile unit 1 has been switched on and the network LED 6 is lit up, thatis to say there is a connection to a mobile radio network. By pressingthe central key 7 once more, a connection can then be set up to aconnection destination, the predefined connection destination beingpermanently programmed into the mobile unit 1, for example by thenetwork operator, the manufacturer of the mobile phone unit or theoperator of the connection destination. “Permanently programmed” meansin the terms of the present invention that simply by accessing themobile phone unit 1 it is not possible to change or delete thepredefined connection destination which is assigned to the central key 7by permanent pre-programming. The programming of the connectiondestination which is assigned to the central key 7 is therefore notcarried out by the user of the mobile unit 1 but is instead provided ona one-off basis by the manufacturer before the mobile unit 1 is sold. Apossible predefined connection destination which is assigned to thecentral key 7 by pre-programming would be, in particular but notnecessarily, a central switching device. The precise operation of thecentral switching device is described below. Pressing the central key 7a second time thus sets up a direct connection to the central switchingdevice which can then connect the user of the mobile unit 1 to anydesired further subscriber, as is also set out below.

The exemplary embodiment of a mobile unit 1 which is illustrated inFIGS. 1a and 1 b is thus dimensioned, by omitting a keypad and replacingthe keypad with a single dialling key in the form of the central key 7,in such a way that it can be worn or carried in a desired way, forexample by means of a clip 9 or can be hung around the neck on a cord(not illustrated), so that, for example, a fitter can work with bothhands and at the same time be instructed online by the mobile unit 1which is hung around his neck and switched on. For this purpose, it ispossible preferably to provide a known earpiece since the fitter cannotof course hold the mobile unit 1 against his ear while working.

A further embodiment of a mobile unit 1 according to the invention willnow be explained with reference to FIGS. 2a and 2 b. The mobile unit 1which is illustrated in FIGS. 2a and 2 b has all the elements of themobile unit 1 illustrated in FIGS. 1a and 1 b. The mobile unit 1illustrated in FIGS. 2a and 2 b differs essentially from the mobile unitillustrated in FIGS. 1a and 1 b in that a plurality of direct connectionkeys 7, 11, 12, 13 are provided. Furthermore, in the exemplaryembodiment in FIGS. 2a and 2 b, the on/off switching function for themobile unit 1 is provided separately from the central key 7, namely inthe form of an on/off switch 15. This on/off switch of the mobile unit 1according to FIGS. 2a and 2 b is located on the side of the casing 4 ofthe mobile unit 1 and can be pushed up or down to switch the mobilephone on and off. In addition, the mobile unit illustrated in FIGS. 2aand 2 b has a display panel 10.

The function of the other direct connection keys 11, 12, 13 of themobile unit 1 in FIGS. 2a and 2 b will now be explained. These directconnection keys 11, 12, 13 have in common with the central key 7 thefact that by means of a single activation they can set up a connectionto a connection destination which is respectively assigned to them. Forexample, the key 13 can be assigned, as connection destination, anemergency-call destination, i.e. an emergency-call organization. Thekeys 11 and 12 can be freely assigned as direct connection keys, forexample for frequently desired connections, by the user of the mobileunit 1, as will be described below.

Even though it is not illustrated, the mobile unit 1 in FIG. 2 can alsohave an interface which permits connection to a known GSM modem.

The keys which can be freely assigned by the user can be assigned asfollows. Firstly, the user sets up a connection to the central switchingdevice by activating the central key 7. As soon as he has a connectionto the central switching device, the user of the mobile unit 1 transfersinformation, namely specifying which connection destination is to beassigned to which of the freely assignable keys 11, 12, to the centralswitching device. The actual assignment (programming) of the freelyassignable keys 11, 12 is then not carried out directly on the mobileunit 1 itself but rather, for example, by means of known DTMFinstructions from the central switching device to the mobile unit 1 viaa radio transmission path. The assignment of the freely assignable keys11, 12 therefore does not take place in each case locally at a mobileunit 1 but instead occurs as a central facility of the switching device.

Before the actual storage of the transmitted assignment, the data whichare transmitted from the central switching device 30 are displayed onthe display 10 of the mobile unit 1. The ultimate storage of theassignment takes place only after this, as a result of the user pressinga key, for example one of the dialling keys 7, 11, 12, 13.

Call number memories, which are assigned to individual keys, and memorylocations of a telephone directory on the SIM card can be assigned bythe central switching device 30. In addition, in response to anappropriate call from the mobile unit 1 to the central switching device30, the central switching device 30 can transmit to the mobile unit 1information which defines the type of call tone or call tones which willbe heard when the mobile unit 1 is used. Furthermore, other features ofthe mobile unit 1, such as call lock-out, call divert, deactivation ofthe greeting text and modification/selection of icons for the memorylocations of the call number memories of the direct dialling keys can bebrought about in response to a call from the mobile unit 1 to thecentral switching device 30 by transmitting appropriate information fromthe central switching device 30 to the mobile unit 1.

A further possible way of programming the freely assignable keys 11, 12is illustrated in FIG. 3. FIG. 3 illustrates the mobile unit 1 in thestate in which it is inserted into a base station 20. In the insertedstate it is electrically connected to the base station 20 in such a waythat an accumulator 14 which ensures that the mobile unit 1 is suppliedwith voltage is charged from the base station 20. The base station 20thus also serves as a charger station for the accumulator 14 of themobile unit 1. As is clear in FIG. 3, the base station 20 has all thecontrol elements which are customary in a conventional telephone, namelya complete control keypad 23 with at least 10 control keys and alarge-format LCD display 21. Furthermore, the base station 20illustrated in FIG. 3 has a central key 22 which performs the samefunction as the central key 7 of the mobile unit 1 which is explainedabove when the mobile unit 1 is inserted into the base station 20. Asalready explained, the accumulator 14 of the mobile unit 1 is charged inthe state in which the mobile unit 1 is inserted into the base station20. Furthermore, the control pad 23 of the base station 20 makes itpossible to carry out the assignment of the freely assignable keys 11,12 of the mobile unit 1. This means that assignment data whichrespectively assign connection destinations to the individual freelyassignable keys 11, 12 are transmitted from the base station 20 to themobile unit 1. As already stated, the assignment of the connectiondestination for the central key 7 cannot be changed by means of the basestation 20 either.

The internal design of a mobile unit 1 will now be explained withreference to FIG. 4. The central component of the electronic system in amobile unit 1 is, as illustrated, a processor 40 which may be, forexample, a commercially available chip for mobile phones. Voice data,which are made available by means of a digitization, using an A/Dconverter 46, of the analogue voice signals which are input through themicrophone 8, are supplied to the processor 40. The processor 40 is alsosupplied with the information from the dialling keys, namely the directconnection keys of the mobile unit 1. The supplying of signals by thecentral key 7 is illustrated as an example in FIG. 4. The key 7 is, asillustrated, connected to a timer 43. The timer 43 thus senses whether,and for how long, the key 7 is pressed. A counter 44, which is in turnconnected to the timer 43, determines the period of activation of thekey 7, which is sensed by the timer 43. The contents of the counter 44are then supplied to the processor 40. Using the timer 43 and thecounter 44, the processor 40 can thus sense whether a key, in the caseillustrated the central key 7, is pressed and for how long a key hasbeen pressed. The processor 40 can thus carry out an evaluation of aswitched state. This means that the processor 40 can, for example, sensethat the central key 7 of the mobile unit 1 is pressed for the firsttime in accordance with the embodiment in FIG. 1. The processor 40implements this switched state 1 in such a way that it switches on thevoltage supply for the mobile unit 1 and at the same time causes themobile unit 1 to be signed on to the corresponding mobile radio network.Since the processor 40 also senses for how long the key 7 has beenpressed during the first activation, it can, for example, cause anemergency call to be transmitted automatically to an emergency-callorganization as connection destination when a predefined time period ofactivation of the key 7 has been exceeded.

Pressing the central key 7 again generates the switched state 2. Thisswitched state 2 is evaluated by the processor 40 to the effect that itsets up the connection to the central switching device. The processor 40thus evaluates the switched states and the time period of activation ofthe individual dialling keys of the mobile unit 1.

An RF module as transmitter/receiver unit is connected to the processor40 in a known fashion, the antenna 2 of the mobile unit being in turnconnected to said unit.

In a conventional mobile phone which has an address book function, whensaid function is activated address book data are usually loaded from afirst dialling register, which can be stored, for example, on a chipcard, into a second dialling register. However, according to the presentinvention the electronic system of a mobile unit 1 has only one diallingregister 47 which contains the assignment data of the connectiondestinations for the freely assignable keys 11, 12 (see exemplaryembodiment in FIG. 2). Therefore, when connection destinations areassigned to a freely assignable key using the central switching deviceor the base station 20 as mentioned above, the contents of the diallingregister 47 alone are modified.

The function associated with operation of the central switching devicewill now be explained in more detail with reference to FIG. 5. FIG. 5illustrates mobile units 1, 101, 201, 301 which can communicate with oneanother in particular via a central switching device 30. FIG. 5illustrates the case in which the mobile unit 1 has set up a radio link33 to the central switching device 30 by means of an antenna 31, and thecentral switching device 30 has transferred this call to a furthermobile unit 201 on a further radio transmission path 34 by means of anantenna 32. The call transfer is carried out here as follows. Forexample, during the initial signing on of a mobile unit, a passwordtable is created in the central switching device 30. Subscriber data,for example the call number or the chip card number (PIN number) etc.,for passwords which are respectively assigned to the subscriber data arestored in the password table. If a mobile unit 1 has then set up aconnection 33 to the central switching device 30 in the manner describedabove, for example using the central key 7, the subscriber data areautomatically transmitted to the central switching device 30simultaneously with the call, for example in the so-called A field ofthe GSM standard. As a result of the transmission of the subscriberdata, the central switching device 30 is thus automatically andimmediately provided, from the mobile unit 1, with informationindicating which subscriber has set up a connection to the centralswitching device 30. After this automatic transmission of the subscriberdata from the mobile unit 1 to the central switching device 30, thecentral switching unit 30 requests a password from the mobile unit 1.This password which is transferred by the mobile unit 1 in response tothe request from the central switching device 30 is then compared in thepassword table in the central switching device 30. This means that thecentral switching unit 30 checks whether the transferred password isactually assigned to the automatically obtained subscriber data. Only ifthis checking of the password table is positive, i.e. if the transferredpassword and the transferred subscriber data actually correspond to thecombination of password/subscriber data of the password table in thecentral switching device 30, does the central switching device 30 switchthe call 33 from the mobile unit 1 to the desired subscriber, in thecase illustrated to the mobile unit 201.

Even if a call is transferred to a further mobile unit in the exampleillustrated, it is still apparent that the call can equally well betransferred from a mobile unit according to the invention to a fixednetwork connection.

This security function provided by the requesting of the password isimportant because no PIN code has to be entered when the mobile unit 1is switched on, so that this possibility of protection against theft ormisuse is eliminated. Non-authorized persons can thus only receive callswith a mobile unit according to the invention. Outgoing calls can onlybe made to the connection destinations which, in the case of theembodiment in FIG. 2, are assigned to the freely assignable keys 11, 12.As a rule, these connection destinations which are assigned to thefreely assignable keys 11, 12 are, however, only significant for aspecific person, with the result that a fraudulent user will not haveany interest in using these predefined connection destinations.

The card contained in a mobile unit is also in itself of little use tothe fraudulent user since insertion of this card into another mobileunit will give rise to an authorization testing procedure which will endnegatively.

Moreover, the password function is also used for the function ofassigning the freely assignable keys 11, 12 in the embodiment of themobile unit 1 according to FIG. 2 from the central switching device 30.After a call to the central switching device 30, a key assignment cantherefore not take place until the password has been appropriatelysupplied. The switching operator in the central switching device 30 thentransmits the corresponding instructions, for example DTMF instructions,to the calling mobile unit. In this way, for example on a mobile unit 1which has been misappropriated, a fraudulent user cannot modify theconnection destinations which have been assigned to the freelyassignable keys 11, 12 by the legitimate user and which are meaninglessto the fraudulent user, to enable him to use the central switchingdevice 30 to assign connection destinations to the freely assignablekeys 11, 12 which are more favourable for him, or more frequentlydesired by him.

In order to make the switching of an incoming call in a mobile unit inthe central switching device 30 particularly fast and simple, when themobile unit 1 is first signed on to the password table in the centralswitching device 30, it is possible, for example, to predefine preferredconnection destinations whose number can be limited by the operator ofthe central switching device 30. Directly after a call by a mobile unit1 and the automatic transmission of the corresponding subscriber data,the central switching device 30 thus determines the preferred connectiondestinations on the basis of the subscriber data of the correspondingpassword table, so that the call can be switched to the preferredconnection destinations with much less effort than if a connection hasto be made to any other desired connection destinations, which is ofcourse also possible, with a comparatively larger search effort.

Therefore, according to the invention the key set can be severelyreduced and nevertheless the complete operational capability of themobile phone is ensured in that access to specific functions of themobile unit are exported, for example, into an intelligent switchingservice or a base station, and therefore does not take place directly atthe mobile unit.

What is claimed is:
 1. In a mobile unit having one or more dialing keys,a method for configuring the mobile unit for a mobile radiotransmission, said method comprising: transmitting voice informationfrom the mobile unit to a central switching center, wherein transmittedvoice information represents a desired assignment of direct dialing keysof the dialing keys of the mobile unit; assigning a connectiondestination to the direct dialing keys of the dialing keys of the mobileunit, based on the transmitted voice information, by using a wirelessdata transfer from the central switching center, whereby a connectiondestination assignment is established; and storing the connectiondestination assignment in a call number memory of the mobile unit. 2.The method for configuring a mobile unit for a mobile radiotransmission, as claimed in claim 1, wherein the connection destinationassignment cannot be modified by direct access to the mobile unit. 3.The method for configuring a mobile unit for a mobile radiotransmission, as claimed in claim 1, further comprising designating oneof the dialing keys as a central key and assigning a switching device asconnection destination for the central key.
 4. The method forconfiguring a mobile unit for a mobile radio transmission, as claimed inclaim 1, further comprising assigning an emergency-call connectiondestination to one of the dialing keys.
 5. In a mobile unit having oneor more dialing keys, a method for configuring the mobile unit for amobile radio transmission, said method comprising: assigning a uniqueconnection destination to each of the dialing keys of the mobile unit,wherein activating one of the dialing keys establishes the uniqueconnection destination assigned to said one of the dialing keys;inserting the mobile unit into a base station, wherein a datatransmission from the base station to the mobile station carries out theunique connection destination assigning; activating a central key toswitch on the mobile unit; activating the central key again to establisha connection to a central switching device; releasing the connection byyet another activation of the central key, and switching off the mobileunit by a further activation of the central key.
 6. The method forconfiguring a mobile unit for a mobile radio transmission, as claimed inclaim 5, further comprising charging an accumulator in the mobile unitwhile the mobile unit is inserted in the base station.
 7. The method forconfiguring a mobile unit for a mobile radio transmission, as claimed inclaim 5, wherein the unique connection destination assigned cannot bemodified by direct access to the mobile unit.
 8. The method forconfiguring a mobile unit for a mobile radio transmission, as claimed inclaim 5, further comprising designating one of the dialing keys as acentral key and assigning a switching device as connection destinationfor the central key.
 9. The method for configuring a mobile unit for amobile radio transmission, as claimed in claim 5, further comprisingassigning an emergency-call connection destination to one of the dialingkeys.
 10. A mobile radio transmission system having a mobile unit, whichhas direct connection keys and a central switching device, the systemcomprising: the central switching device having a password table whichcontains subscriber data with a respectively assigned password; meansfor transferring subscriber data and a password to the central switchingdevice after a connection from the mobile unit to the central switchingdevice has been established; means for comparing the transferredsubscriber data and password with the password table; in the centralswitching device, means for assigning a connection destination to eachone of the direct connection keys through means for transferringwireless data from the central switching center to the mobile unit, theassigning taking place in response to a corresponding transmission ofvoice information from the mobile unit to the central switching device;and a memory of the mobile unit for storing the transferred assignment.11. The mobile radio transmission system, as claimed in claim 10,further comprising a base station into which the mobile unit can beinserted to carry out the assigning of said each one of the directconnection keys, except for a central key, by means for transmittingdata from the base station to the mobile unit.
 12. The mobile radiotransmission system, as claimed in claim 11, further comprising: thebase station includes charging means; the mobile unit includes anaccumulator which can be charged while the mobile unit is inserted inthe base station.
 13. The mobile radio transmission system, as claimedin claim 11, wherein a list of possible connection destinations, each ofwhich is assigned to a password and respective specific subscriber data,is provided in the password table of the central switching device.